Some people say that you can run pump gas. 90 octane or even mix it 50/50 with 100LL. Some people say they would never put pump gas in their bird?

http://www.autofuelstc.com/approved_eng ... ames.phtml

You don't want to use fuel with Ethanol. Mixing auto fuel and 100LL is no big deal. You do need the STC to get the paperwork that will prevent you from crashing into a school for handicapped children.

Running 87 in that engine will be no problem. They are pretty dang low compression. Ethanol is not legal on the stc for auto fuel BUT it works absolutely fine.

As with many things in aviation, there's what you can do from a practical standpoint, and what you can do and still retain your pilot certificate and/or get your claim paid by your insurance.

Fuel octane is important only in the sense that fuel volatility should match your compression ratio. Too volatile (low octane) and it can detonate; hard on the engine. You can mix 91 pump gas and 100LL fine, and it should achieve a median octane rating.

Fuel that is oxygenated with ethanol presents 2 risks: 1) Corrosion/degradation to components of the fuel system incompatible with alcohol(generally natural rubbers I think, if present), and 2) the ability to hold water in suspension and then have it become water again at an inopportune time, like when the engine is trying to burn it. An O-320 or O-360 will burn 87 octane 10% ethanol fuel just fine, these two prior-mentioned considerations notwithstanding.

Then there's the legality part. In a certified standard category aircraft, you have to have a STC for the fuel, and most of them specify non-ethanol, sometimes called "clear" gas. It's become so poorly available these days that the stations or suppliers that do have it tack on a pretty premium, but it usually attracts the farmers and landscapers from miles around.

I have been running alcohol free car gas for close to 20 years and over 1000 hours of flying onto O2 hundred and 0235 Taylorcraft with no issues in some cases and situations runs better than av gas

I run 93 octane e0 with no issues

Once you start running Auto fuel in that O-235, you'll never want to go back to straight 100LL. I've ran mine for the last 30 years on auto fuel. It HATES 100LL. Runs rough and has to be leaned out with 100LL. Even with projected nose plugs. Back when I could still get 80 octane (red fuel), I did a 80 octane in one tank vs auto fuel in the other. Guess which one ran smoother? I actually try to run a mixture of 75% auto to 25% 100LL just to keep the valves and guides happy. Also a dose of red vitamins (Marvel Mysterty Oil) as well for keeping the insides clean. I believe somewhere on one of the auto fuel stc sites it lists a ratio of 75% auto fuel with 25% 100LL yields the same lead content as 80 octane. Since that is what the engine was designed to run on, I try to most of the time feed it close to the same lead content. Disclaimer, I know nothing. Just following what all the old farmers have told me keep all their old tractors running all these years.

If I'm stuck in Canada with nothing but 87 octane with ethanol would you guys run it?

I have a buddy that would if he was in that situation.

Steve

I run regular 87 in my 0-300. it defiantly runs better, stronger. Every once and a while ill put a little bit of 100LL in with a tank to give some lead content, but thats it. Us here in Alaska are very lucky because we dont have ethanol in our fuel. go ahead and run it and dont look back.

Cody986 wrote:Thanks for all the info it's great! A lot of useful info.

So if I'm stuck deep in Canada with nothing but 87 octane with ethanol would I be safe to run it in my plane? Would you guys run it if you had to?

You're talking like there is no avgas in Canada......there is lots of avgas in Canada.

Don't worry about it. If you had to run some auto gas, it wouldn't hurt a thing.....buy the highest octane you can find, and preferably with no alcohol added.

But, finding gas in Canada is easier than doing so in Alaska, in my experience.

MTV

PAMR MX wrote: Ethanol is not legal on the stc for auto fuel BUT it works absolutely fine.

A buddy went down when the E-10 he was running swelled the rubber fuel lines shut.

I run E-10 just fine, but I have SAE spec fuel lines and a Rotax engine that has the appropriate stuff in the fuel pump / carb.

Geoffrey Thorpe wrote:A buddy went down when the E-10 he was running swelled the rubber fuel lines shut.

I run E-10 just fine, but I have SAE spec fuel lines and a Rotax engine that has the appropriate stuff in the fuel pump / carb.

This is why anyone who's interested in running E10 should be very familiar with their entire fuel system and what's it's made from. My Bearhawk is plumbed entirely (well, only 40% thus far) from 5052 aluminum. The places where I will use hose I will be certain to use a modern alcohol-stable synthetic like Tygon. Have to be careful about what O-rings are used in valves too.

steve wrote:I have a buddy that would if he was in that situation.

And be aware of what materials are used inside your carburetor, if you have one.

MTV

Until 2009, I ran whatever came out of the pump at the local station in whatever little airplane I was flying, including 0-540s in spray planes. I don't know what they put in automobile gas now days, but it is unfortunate that lawyers and insurance companies have removed so many options from the life of a pilot. Airplanes engines don't run without gas. I would put some in if the tank was very low at all.

YA...i get all that...let me just say after buying a SNEW motor or 2 that i run the absolute best fuel i can get my paws on...i think clean auto gas is ok in the smaller motors ...but not sure why i would run it in anything over a 360 just to save a few bucks...but, if u like running them super hard all the time and etc and maybe u dont have to pay for the motor out front, do what works i guess...here in idaho i seem to fly over so much desolate ruff stuff, and quite a bit of nite ops...i want less chances of a problem related to fuel...just some thoughts...i would treat that motor like your life depended on it...cuz...it does....! safe travels my friends....

Geoffrey Thorpe wrote:

PAMR MX wrote: Ethanol is not legal on the stc for auto fuel BUT it works absolutely fine.

A buddy went down when the E-10 he was running swelled the rubber fuel lines shut.

I run E-10 just fine, but I have SAE spec fuel lines and a Rotax engine that has the appropriate stuff in the fuel pump / carb.

So what kind of fuel line was it??

I've been burning quite a bit of regular E-10 lately, but the other day in S. Dakota I noticed that the gas station I was at had some regular E-85, I opted out of that, and though I only need regular I got the premium because it was E-10.

Buying mo-gas at the busier stations somewhat assures fresher fuel due to the high turnover. But if I'm in a strange town and see two stations across the street from each other, and one is a nickel cheaper, I'll go to the cheaper one. I never look at what brand of fuel it is, don't really care, been doing it that way for 35 years and have never had any kind of fuel issue. Whatever makes a pilot feel safe in their fuel choice, many use premium in their cars when regular is all they need, more power to them (pun intended) if that makes them feel better. Same with the mo-gas in planes. I never put av gas in the Rotax, not in years now, since getting over my initial fear of ethanol.

regular E-85

Maybe should explain E85 a little. It is 85% ethanol and 15% gasoline. That is the blend in the summer and in the cold months in the upper Midwest, the blend actually goes to 70% ethanol since ethanol in high concentration isn't as volatile as gasoline. It has low vapor pressure and makes starting harder. E85 that is full strength(85%) is about 105 octane but needs more fuel flow since it is lower btu's per gallon. Also I found this when Steve Pierce mentioned that he knew what "drip gas" was down in Texas where he lives. Just think, if there was no ethanol to blend with the drip gas, where would it go.

Oh yea, drip gas too

Natural gasoline is often used to denature ethanol produced for E85. Natural gasoline has a lower octane content than conventional commercial distilled gasoline, so it cannot normally be used by itself for fuel for modern automobiles. However, when mixed with high concentrations of ethanol such as mid-level blends, like E50 or E85, the octane content is raised high enough to be used easily in flex-fuel vehicles. It may be sourced from production of natural gas wells (see "drip gas") or may be produced by extraction processes [3] in the field, as opposed to refinery cracking of conventional gasoline.

It is also used to denature(poison) ethanol at the ethanol plant. Usually, 2 to 5% depending on economics.